Just keep in mind that this sounds like it's running a lightweight VM of some sort - the bash window cannot run or interact with Windows programs.
I wonder what the technical reason behind this is - as far as I understand their approach, this is more of a syscall translation thingamajig than a lightweight VM like CoLinux. There's probably still some kernel object translation going on as well (like file handles) which might complicate windows<>linux communication, and probably some security concerns as well.
Would be interesting with some more implementation details, as well as a comparison to existing stuff like CoLinux.
I have no idea why Microsoft took the route it did when these tools are readily available.
Perhaps because it might be an easier route to running stuff than porting? Perhaps to be able to support closed-source linux binaries?
I personally can't think of any use cases where this would be better than using the MinGW binaries, but it's cool tech